The prevalence of chronic kidney disease (CKD) in the United States is now estimated at 13%, and is associated with significant morbidity and mortality (Coresh et al., Am J Kidney Dis 2003; 41(1):1-12). In particular, approximately 100,000 Americans develop end-stage kidney disease (ESKD) each year. The cumulative life-time risk for ESKD varies by race, and is approximately 7.5% for African-Americans and 2.1% for European Americans (Kiberd et al., J Am Soc Nephrol 2002; 13(6):1635-44). In particular, African-Americans have a disproportionate risk for several forms of CKD, among them diabetic nephropathy (Cowie et al., N Engl J Med 1989; 321(16):1074-9), hypertensive nephrosclerosis (Toto, Kidney Int Suppl 2004(92):S102-4), lupus nephritis (Fernandez et al., Arthritis Rheum 2007; 57(4):576-84), focal segmental glomerulosclerosis (Kitiyakara et al., Am J Kidney Dis 2004; 44(5):815-25) (FSGS), and HIV-associated nephropathy (a distinct form of FSGS, also termed collapsing glomerulopathy).
FSGS is a clinical syndrome involving podocyte injury and glomerular scarring, and includes genetic forms with Mendelian inheritance, reactive forms associated with other illnesses (including HIV-1 disease) or medications, and an idiopathic form, which accounts for the majority of cases (Barisoni et al., Clin J Am Soc Nephrol 2007; 2(3):529-42). African-Americans have a 4-fold increased risk for sporadic FSGS (Kitiyakara et al., Semin Nephrol 2003; 23(2):172-82) and an 18-fold to 50-fold increased risk for HIV-1-associated FSGS (Kopp et al., Kidney Int Suppl 2003(83):S43-9; Eggers et al., J Am Soc Nephrol 2004; 15(9):2477-85). Individuals of African ancestry also have increased risk for FSGS in other geographic regions, suggesting that genetic factors contribute to these disparities (Kitiyakara et al., Semin Nephrol 2003; 23(2):172-82).